Urinary amylase isoenzymes and amylase polymorphism variants in families with diabetes mellitus type 1.

Insulin-dependent diabetes mellitus type 1 is an autoimmune disease of pancreatic beta-cells with a certain genetic predisposition that is not yet clear. In spite of the confirmed association of diabetes mellitus type 1 with several HLA haplotypes it is considered that other loci must be involved for total genetic susceptibility to the disease. The relationship of insulin deficiency and decreased pancreatic amylase activity suggests that insulin itself is a direct activator of amylase gene expression. Endocrine pancreatic function was monitored by the indirect non-invasive method of urinary pancreatic amylase activity determination (expressed in percentage of total amylase activity) in diabetic children, their parents, healthy sisters and brothers, and in a separate group of women with diabetes type 1 of over 20 years duration. The incidence of hereditary amylase polymorphism variants in these subjects was also ascertained. Decreased pancreatic amylase activity in urine (under 58%) was found to be a characteristic trait in diabetics, and a susceptibility trait in asymptomatic family members. Normal pancreatic amylase activity (66.7 +/- 5.4%) is rare in diabetic patients type 1, but may be seen as a favourable prognostic trait, representing resistance to diabetic complications. The results support the suggestion that hereditary predisposition to the disease is inherited from the father rather than the mother, and that heterozygous amylase polymorphism variants protect their carriers against diabetes mellitus type 1.